Waxed thread sewing machine



p 22, 1953 H. w. BOOTHROYD ET AL 2,652,794

WAXEZD THREAD SEWING MACHINE Filed Aug. 22, 1950 Inventors Harold W Boot/zmyd Alvin, J ZL'n/r, Jr;

Patented Sept. 22, 1953 WAXED THREAD SEWING MACHINE Harold W. Boothroyd, Beverly, and Alvin J. Zink, Jr., Andover, Mass., assignors to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application August 22, 1950, Serial No. 180,766

Claims.

The present invention relates primarily to shoe sewing machines, although it also is of more general application to other machines employing waxed thread and requiring heat to render the thread flexible and capable of manipulation duringoperations, Examples of such machines are disclosed in United States Letters Patent No. 1,971,575, granted August 28, 1934, and No. 2,220- 112, granted November 5, 1940, both in the name of" Alfred R. Morrill.

The sewing machines illustrated in the patents referred to are capable of use with relatively heavy thread requiring a coating of wax applied in a molten condition. In order to insure consistent flexibility in the thread as it reaches the sewing point local applications of heat are needed beyond the thread supply. To insure proper application of heat, heating units have been employed with heat conducting and distributing members past which the thread is led. In certain instances the thread is led through guide tubes having heating units clamped thereto. In such instances, however, it has been found that a guide tube may be overheated along a section in contact with a heating unit and insufficiently heated along other sections.

An object of the invention is to provide a heated thread guide tube for conducting thermoplastically waxed thread to the sewing point in a shoe sewing or other machine in which the thread is maintained in proper heated condition even though conducted through relatively great distances without overheating or underheating the thread along any of its portions. Another object isto simplify and improve the construction and operation of heated thread conducting tubes for waxed thread machines of the type referred to. To these ends the present invention is illustrated as embodied in a thread manipulating machine having a main frame, thread handling devices in the frameand a waxed thread supply, in which means is provided for conducting the thread from the supply to thehandling devices comprising a double walled tubemounted in the frame, an electrical heating unit located between the walls of the tube, an electrical outlet box surrounding one end of the tube and unitary clamping means arranged at thesame end of the tube as the outlet boxfor securing both the tube and the outlet box in place in the frame of the machine.

- These and other features of the invention, as hereinafter described and claimed, will be apparentfrom'th'e following detailed description,

taken in connection with. (the accompanying drawings, in which:

- Fig. 1 is a new in right side elevation partly broken away and in section of the frame and of some of the operating parts in a Waxed thread shoe sewing machine embodying the features of the present invention;

Fig. 2 is a section detail view on an enlarged scale of the heated thread conducting tube of the machine illustrated in Fig. 1;

3 is a detail view of a tube securing clamp illustrated in Fig. 1; and

Fig. 4 is a detail View on a still further enlarged scale of the upper end of the heated thread conducting tube.

The machine illustrated in the drawings is a thread handling machine comprising a curved hook needle chain stitch welt shoesewing machine intended to employ thread coated with hot wax and is similar in construction and mode of operation to those of the Morrill patents above identified. Besides the usual stitch forming devices, the machine-is provided with means for supplying thread coated with thermoplastic wax, from which the thread is led through a guide in the form of a tube for conducting it into the machine between the thread supply and the stitch forming devices.

Referring to the drawings, the machine has mounted in its main frame 4 the stitch forming devices including a curved hook needle 6, a curved awl 8; a needle looper I0, a welt guide 12, a back rest I4, and a thread tension wheel I6, all operated or controlledfrom a main sewing shaft I8. To conduct the thread from a thread supply, comprising a wax pot 2|], to the thread tension wheel there is mounted in the frame of the ma chine a tube 22; extending diagonally upwardly from the wax pot, which is secured to the rear of the machine frame.

If an attempt is made to heat the tube 22, by the use of a conventional heating unit secured to the tube, the tube will befound to conduct heat insufficiently for maintaining the thread throughout its length at a proper temperature. If the tube is highly heated at one location by clamping a heating unit thereto the thread and Wax become scorched at that location without effectively heating it elsewhere along the length of the tube. Local overheating causes a deposit of scorched Wax in the heated section of the tube and in other sections solidified wax may accumulate as a result of underheating. Thus, eventually the thread tube becomes blocked so as to impede seriously the passage of the thread from the supply to the stitch forming devices.

To overcome these difficulties in the illustrated machine, the tube 22 for conducting the thread between the thread supply and the stitch forming devices is made of double walled construction in which the walls are separated to provide a space between them. The walls of the tube are essentially separate tubes of different diameter, one inside the other, joined together at their upper ends by an hermetic seal 24. Along the length of the tube within the space between the walls of the tube is disposed and distributed a heating element consisting of a series of coils of flat electrical resistance wire 26. To maintain proper separation of the wire from the tube, the coils are incased in sheets of insulation 28, both inside and outside their diameters. At the upper end of the tube the wire 26 is formed into a reverse bend 30, being carried into parallel relationship with itself and having both ends of the wire connected to insulated lead-in conductors 32, at the lower end of the tube. Surrounding the lead-in conductors 32, is a glass seal 34 supported in a metal terminal container 35 for enclosing a quantity of granular insulation 38, all parts of the container being sealed to the separate walls, of the thread conducting tube and communicating with the space between the walls. To secure the thread conducting tube in place the upper end is engaged in a close fitting opening 40 in the upper portion of the machine frame, and at its lower end the tube is made fast in unitary clamping means of a particularly effective form.

The unitary clamping means for the thread conducting tube not only secures the tube in place in the machine frame, but also prevents displacement of an outlet box 42 loosely surrounding and protecting the lead-in container 36. For clamping the tube and the outlet box in place the outlet box has an integral perforated collar slidably surrounding the thread conducting tube at the same end of the tube and between the collar and the tube is a split sleeve 44. To prevent dislodgement of the sleeve 44 from inside the collar, a dowel pin 45 passes through the collar and into the sleeve. Engaging the sleeve to clamp the parts in position is a single screw 48 threaded into the side of a drilled boss on an attaching fixture plate 50 secured to the rear of the machine frame at the same end of the tube 22 with the outlet box. The boss on the fixture plate is bored and surrounds the collar on the outlet box. The clamp screw 48 passes through the perforation in the collar into engagement with the split sleeve 44 to distribute the clamping pressure along the outer wall of the thread tube, forcing the sleeve against the collar of the outlet box and in turn engaging the undersurface of the collar with a clamping pressure on the boss of the fixture plate 50. The screw 48 thus provides a unitary means for clamping both the thread tube and the outletv box. For convenience in assembling the thread tube in the outlet box and machine frame, the rearward side of the box is closed by a removable cover 52, and the upper side of the box has a knock out opening to receive a conventional electrical fixture 54.

To offset the heat conducting action of the tube clamping means including the sleeve 44, the set screw 48, and the fixture plate 50, the coils of the heating element are concentrated to provide greater heating capacity along the clamped portion 56 of the thread tube. A greater heating capacity, lso, is provided along the upper end portion 58 of the thread tube which is engaged by the opening 40 in the machine frame. This result is obtained merely by spacing the coils of the resistance wire 26 in closer relationship along the corresponding parts of the thread tube.

The thread tube also passes through an opening of substantially larger dimensions than the outside of the tube. This larger opening is formed in a partition inside the machine along the central portion of the thread tube and serves to reduce vibration of the tube while providing a heat insulating air gap between the tube and the partition. Because of the heat insulating gap, there is no necessity of increasing the capacity of the heating element along this portion of the tube.

The nature and scope of the invention having been indicated and a particular embodiment having been described, what is claimed is:

1. A waxed thread shoe machine having a main frame, a needle and other stitch forming devices in the frame, and a Waxed thread supply supported by the frame, in combination with means for conducting the thread from the supply to the stitch forming devices while maintaining the thread in heated condition comprising a double walled tube mounted in the frame, an electrical heating element between the walls of the tube, an electrical outlet box at one end of the tube and means in the frame for clamping the thread conducting tube and the outlet box, said electrical heating element being formed into coils disposed in closer relationship along, the clamped area of the tube than along its unsupported length, and said frame having a central guide opening of larger, dimensions than the outside of the tube to provide a heat insulating air gap between the tube in? the frame along the central portion of the 2. A guide for conducting a thread treated with thermoplastic wax to the operating point of a thread handling machine, comprisin a double walled tube, the walls of which are separated and disposed one inside the other to form a space between them, an electrical heating element distributed along the space between the Walls of the tube, an electrical outlet box surrounding the tube at one end, an attaching fixture at the same end of the tub with the outlet box, and unitary clamping means carried by the attaching fixture and also arranged at the same end of the tube as the outlet box for securing the tube in the attaching fixture and the outlet box from displacement from the tube.

3. A guide for conducting a thread treated with thermoplastic wax, comprising a double walled tube, th walls of which are separated and. disposed one inside the other to form a space between them, an electrical heating element distributed along the space between the walls of the tube, an electrical outlet box surrounding the tube at one end, an attaching fixture plate engaging the outlet box in surrounding relation to a portion thereof and screw threaded means carried by the fixture plate passing through the outlet box for clamping the outlet box to the tube and the outlet box within the fixture plate.

4. A guide for conducting a thread treated with thermoplastic wax, comprising a double walled tube, the walls of which are separated and disposed one inside th other to form a space between them, an electrical heating element between the walls of the tube, a terminal container sealed to the walls of the tube and communicating with the space between the walls, lead-in conductors connected to the electrical heating element between the walls of the tube and supported in the terminal container, an outlet box loosely surrounding the lead-in container, an attaching fixture plate engaging the outlet box, a

5 setscrew threaded in the fixture plate and a sleeve between the thread conducting tube and the outlet box against which the setscrew acts to distribute the clamping pressure of the setscrew along the outer wall of the thread tube.

5. A guide for conducting a thread treated with thermoplastic wax, comprising a double walled tube, the Walls of which are separated and disposed one inside the other to form a space between them, an electrical heating element comprising a wire formed into coils between the Walls of the tube, an electrical outlet box disposed in surrounding relation to and at one end of the tube and screw threaded means passing through a portion of the outlet box and acting on the outlet box to clamp it to the tube, said electrical heating 6 element having coils disposed in closer relationship along the area of the tube clamped within the outlet box than along other portions of the tube.

HAROLD W. BOOTHROYD. ALVIN J. ZINK, JR.

References Cited in the file of this patent UNITED STATES PATENTS 

